1. Field of the Invention
This invention relates to an image forming apparatus, and more specifically to an electrostatic type copying machine having a photoconductor and designed to copy an optical pattern image which is the information formed on an object, by forming on the photoconductor a latent image corresponding to the image, rendering the latent image visible, and electrostatically transferring the visible image from the photoconductor to recording material.
2. Description of the Related Art
Most electrostatic type copying machines have a photoconductor, a developing mechanism, a material delivering mechanism, and a cleaning unit. A latent image of the optical pattern image of the object is formed on the photoconductor. The developing mechanism supplies developer (generally known as "toner") to the photoconductor, thereby developing the latent image into a visible one. The material delivering mechanism supplies the recording material, such as a sheet of paper. The image is electrostatically transferred from the photoconductor to the recording material to make a hard copy. The cleaning unit removes the residual developer from the photoconductor.
In order to transfer the image from the photoconductor to the recording material, a voltage as high as several kilovolts is applied to the photoconductor, thus electrically charging the photoconductor. The photoconductor is discharged upon each completion of transferring an image from the photoconductor to a sheet of paper. Hence, the photoconductor is repeatedly charged and discharged as the image is copied many times. As is known in the art, the more times the photoconductor is charged and discharged, the more its charge-discharge readiness will be deteriorate. It is also known that the cleaning unit is likely to scratch the surface of the photoconductor when it is pressed onto the photoconductor to remove the residual toner therefrom after the visible image has been transferred to the sheet of paper.
Therefore, it is necessary to periodically replace the photoconductor with a new one. Also it is necessary to adjust, occasionally, the pressure at which the cleaning unit is pressed onto the photoconductor to remove the residual developer. In other words, trained servicemen often need to do maintenance on the copying machine.
A serviceman is called when the user of the copying machine finds that the machine does not work well. It is virtually impossible for the user to point out to the serviceman, precisely and correctly, what is the trouble with the machine or where in the machine the trouble is happening, because the user does not know much about the copying machine. In most cases, it takes the serviceman a considerably long time to determine the trouble and repair the machine to eliminate the trouble.
The periodic maintenance of the copying machine also requires some time. When trouble is found in the machine, more time is required to eliminate the trouble. Even if the trouble is small, the serviceman needs to spend much time to fix it if he or she has not repaired or inspected this particular copying machine.
No matter whether the serviceman examines and repairs the machine at the request of the user, or performs periodic maintenance on the machine, the copying machine is left unusable for a long period of time. This obviously jeopardizes not only the operating efficiency of the copying machine, but also the reliability of the machine.